I've seen some cool art and scenes from the Cowboy Bebop which had trade lanes made up of what looks like large rings that accelerate and deccelerate a ship.

I wanted to replicate a system like this for Warlords making use of the ITN (interplanetary transportation network). Now the actual idea I had would be another question (seeing as this is just about the concept)

Would using external rings or other technology help make the ITN faster and become a practical and reliable shipping method? Is it practical or is this construction too monumental to work?

Note: independent ships and lanes would still exist due to some materials needing rapid transportation or ships trying to avoid the lanes for various reasons.

  • 1
    $\begingroup$ You may want to add a bit more info on how the rings are going to be used. Are they in pairs, i.e. one at the source and one at the destination, or are they placed along the entire shipping lane? Are they in orbit around planets and designed for interplanetary shipping, or at the edge of solar systems to connect stars? $\endgroup$ – Giter Jul 31 '18 at 14:04
  • $\begingroup$ @Giter Honestly I have no idea which system would work best. $\endgroup$ – Celestial Dragon Emperor Jul 31 '18 at 14:32
  • 2
    $\begingroup$ Never seen Bebop but this sure does remind me of the fast travel system from the 2003 PC game Freelancer. Those were just some rings and glow effects to make you travel much faster through space. They were placed along the shipping lane and didn't act as gates as there was a mission where you needed to help out a large transporter that was being attacked by pirates and pushed out of the lane (by destroying one of the rings if I remember right). $\endgroup$ – Otto Abnormalverbraucher Jul 31 '18 at 15:58
  • $\begingroup$ Bolos (or Momentum Exchange Tethers if you like being verbose :-)). See e.g. en.wikipedia.org/wiki/Momentum_exchange_tether $\endgroup$ – jamesqf Jul 31 '18 at 17:42

The rings are super magnets.

If the rings are super magnets they can accelerate ships via electromagnetic repulsion. A set of rings, for example 10 or 100 can be used to apply the repulsion affect several time to accelerate a ship very fast forward. You may want to have a corresponding set of rings on the other side, at the destination, to decelerate incoming ships in the same way to make this system really efficient.

Is it practical? It is probably a lot more practical than using rocket fuel. The ships can be lighter since they don't have to carry the fuel themselves. So they can be smaller, cheaper, etc. Building rings like this in space probably isn't too difficult either since the mechanics behind it and the size are not too absurd.

Coordinating everything so that they line up would be the hardest part. This is because planets move. So lining up the rings for acceleration at your departure point, so that you reach the rings for deceleration at your arrival point, may be a difficult math equation to solve.


So how do we address the problem that when a ship moves forward it will push the rings backwards? (Newtons 3rd law)

The rings don't have to be completely stationary satellites. They can be space ships too, but designed to just stay around some region of space.

The rings can even be one large super object instead of separate rings, or attached to asteroids, and be re-attachable to others when one moves too far.

The rings can have all the usual bells and whistles for navigation. How bulky the rings are isn't really an issue for interstellar travel since they wont be travelling far. The real benefit is in having the ships that are ejected not have to carry lots of fuel, so they can be accelerated to very fast speeds fairly efficiently. This is because the ships can lower their mass by shedding the mass of their fuel, which is instead handled via the electromagnetic ring.


Force = Mass x Acceleration,

Acceleration = Force / Mass.

By lowering mass we can increase the amount of acceleration from the same force.

And Thanks @Alice:

There are also ways to maintain or correct orbit without expending reaction mass, such as solar sails and tethers.

  • 1
    $\begingroup$ Dealing with the recoil from accelerating ships will indeed be a problem for the rings. Assuming they are in a heliocentric orbit somewhere outside of the Earth's, they will need a regular resupply of fuel to prevent their orbit from either increasing or degrading after each launch. That is, unless they can balance out their launches and on average, alternate the direction of their "firing". I would assume that the required heading of the spaceships would ultimately be determined by their destination, not convenience to the launching station. It would require careful planning. $\endgroup$ – abestrange Jul 31 '18 at 18:38
  • 1
    $\begingroup$ Assuming there are several of these, their orbit might be managed by careful planning and scheduling the departures from them. It would require a dedicated crew, but it might be something more akin to air traffic controllers today. $\endgroup$ – Tyler S. Loeper Jul 31 '18 at 18:45
  • 1
    $\begingroup$ I agree that a network of them could be poised to boost crafts into higher and higher orbits, and would probably be necessary for actual utility. The problem of dealing with recoil remains, however. The most ideal scenario I can think of would be that refueling craft would regularly harvest resources from asteroids and deliver them to the stations. They could use ion thrusters to slowly counteract their recoil forces, or simply launch an inert chunk of iron or slag in the opposite direction from time to time, which would come with its own risks. $\endgroup$ – abestrange Jul 31 '18 at 18:50
  • 1
    $\begingroup$ To some extent this could also be cancelled out by the orbit of the rings themselves, which are inherently circular as well. If they are for example in orbit around a central star then on the inner orbit (orbit closest to destination) launches will decrease the orbit radius, and during the outer orbit period (farthest from destination) launches will increase the radius. Its not perfect, but stabilizing the rings orbits could also be managed with this. $\endgroup$ – Tyler S. Loeper Jul 31 '18 at 19:04
  • 1
    $\begingroup$ It would be quite fortuitous if inner and outer orbital launches canceled out perfectly, or at least close enough to easily maintain the discrepancies. Part of it depends on the force the rings can apply. If they cannot completely overcome the crafts existing orbital velocities, then launching them into a retrograde orbit would not be possible. The only option then is to lower their current orbital velocity to lower their orbit, which is almost certainly going to require exact parameters to align with with a target planet's orbit. Hopefully they balance with the outer launches. $\endgroup$ – abestrange Jul 31 '18 at 19:16

Space has a lot of well space in it, there's a quote from Hitchhikers Guide I should be using but I can't be bothered looking it up right now about just how huge space is. The point is that the volume of shipping you would need to be doing to make traffic lanes for shipping either practical or necessary is staggering, that's problem one.

Issue two, destinations move around in space relative to each other so the lanes would be moving around, all over the place, all the time. So while a laneway that allowed for faster shipping of goods might be desirable keeping it aligned would be prohibitively expensive.

So lanes not so much, you might have gates that allow instantaneous, or at least speed-of-light transition of ships from one place to another, these may only need to be turned to face each other or possibly only need tracking data for a software based alignment. The particular cost:benefit situation is a matter of the exact setting and so is a story-based element that you'll have to decide and/or justify to yourself.

I don't remember the Bepop rings being used as accelerators, just for breaking maneuvers on final approach towards planets but I haven't watch the series in a long time.


The issue isn't the rings (which are likely parts of a massive mass driver system) but your use of the ITN. The ITN is essentially a shifting zone of gravitational interactions between planets and the Sun, but the effect is very slight and a spacecraft using the ITN might be considered analogous to a leaf floating down a very slow moving stream. Using the ITN might take years, decades or even centuries to get from place to place in the Solar System.

A spacecraft being launched using a mass driver can be accelerated to any arbitrary speed, only limited by the amount of acceleration the ship, ships systems and crew (if any) can take. There is nothing to prevent you from accelerating the ship to any speed ranging from the minimum orbital speed needed to reach the next planet (a Hohmann transfer orbit) to 72 km/sec, the maximum velocity an unpowered object can remain in solar orbit. Of course, more speed requires more energy and much more acceleration in any given length of mass driver, so the general rule would be to use this to send cargo on Hohmann transfer orbits in order to economize on energy use. Bulk cargos could be sent via unpowered pods to distant markets, where similar mass drivers would decelerate them to a stop.

For manned ships, using a mass driver to kick start your voyage would save a lot of fuel needed to accelerate or decelerate, so given a large and powerful enough mass driver, this would likely be the favoured solution as well.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.